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Photocatalytic activity of hydrothermal titanium dioxide
Lepičová, Martina ; Jančovičová, Viera (referee) ; Veselý, Michal (advisor)
Hydrothermal synthesis is one of the most widely used methods for preparing nanoparticles of titanium dioxide. The process carried out at elevated temperatures and pressure, which facilitates the transformation of amorphous to crystalline titanium dioxide. Change of reaction conditions of the process (reactants concentration, temperature, time, pH, etc.) leads to change in morphology, microstructure and crystallinity of titanium dioxide nanoparticles. In this work the method of titanium dioxide preparation is briefly described. The titanium dioxide was prepared from a precursor titanium oxochloride and potassium hydroxide as the precipitating agent. Thus prepared titanium dioxide was immobilized on a glass substrate by material printing. This is a modern, highly precise and contactless method for preparing thin films. The photocatalytic activity of printed thin films of titanium dioxide was investigated by degradation of 2,6-dichlorindophenol at different irradiance. It was found that the sample prepared by hydrothermal treatment at 160 °C shows very similar photocatalytic activity to Degussa P25.
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Deposition and characterization of SA layers from vinyltriethoxysilane
Veverka, Miroslav ; Veselý, Michal (referee) ; Čech, Vladimír (advisor)
Development of composite material is very much progressive sector and leads to evolution of material with new property. This type of material has one, but important deficiency. It is small adhesion armature to matrix. My study is sight on improvement adhesion the surface by deposition self assembled (SA) monolayer from organosilanes. Property of this layer, like thickness, surface tension, homogenity and wettability, was evaluated by the contact angle measurement and spektroscopical elipsometri.
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Kinetics of photocatalytic and electrophotocatalytic degradation of swimming pool water model pollutants
Morávková, Eva ; Cihlář, Jaroslav (referee) ; Veselý, Michal (advisor)
This diploma thesis deals with the coating and printing of thin layers based on nanoparticles of titanium dioxide and organosilica binder on various substrates. The influence of the ratio of the both components on the activity of the prepared immobilized layers was studied. Five compositions with different ratios of TiO2 and binder were prepared. The work focuses mainly on the study of photocatalytic and photoelectrocatalytic properties of prepared layers. It was also important to characterize the mechanical properties of the layer such as hardness or adhesion. Both photocatalytic and photoelectrocatalytic activity were determined by monitoring the degradation of the model pollutants in aqueous solutions. The dye Acid Orange 7 and UV filter 2-hydroxy-4-methoxybenzophenone were used in conjunction with UV/VIS spectroscopy or high performance liquid chromatography techniques. Both photocatalytic and photoelectrocatalytic activity were expressed using kinetic characteristics.
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Utilization of Deep-UV-LED for photocatalytic activity study
Knobová, Klára ; Zmeškal, Oldřich (referee) ; Veselý, Michal (advisor)
This bachelor thesis deals with the influence of several light emitting diode sources of UV light on photocatalytic activity of titanium dioxide. The theoretical part involves their properties and production and covers existing knowledge. DEEP-UV light emitting diodes with different wavelength of emitted light and their influence on the rate of photocatalytic degradation of stearic acid are studied in the experimental part.
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Material printing of ozone dosimeters
Petříčková, Zuzana ; Čeppan,, Michal (referee) ; Veselý, Michal (advisor)
This study presents various methods of measuring ozone and consolidates current state of knowledge in the field of disposable printed ozone dosimeters. The paper also identifies prospective dyes for preparation of ozone dosimeters available on the market. Information gathered from literature review was used to prepare dosimeters based on two different dyes. These were calibrated for screen printing technology and their sensitivity to ozone was optimized to achieve visual detectability. Prepared samples were observed and studied while being exposed to ozone. Then, long term mechanical and chemical properties of these were tested in order to identify appropriate conditions for storage.
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Outdoor applications of photocatalytic materials
Šimončičová, Monika ; Králová, Marcela (referee) ; Veselý, Michal (advisor)
This bachelor thesis deals with the evaluation and optimization of the method for the determination of photocatalytic activity of facade coating layers with and without photocatalyst admixture titanium dioxide. The layers are tested by the photooxidation of the organic dyes Acid orange 7 and methylene blue, which are model compounds of pollution. Degradation of organic dyes is monitored by UV-VIS spectrophotometry and evaluated by determination of rate constants and specific photoactivity. The aim is to find out which of the facade coating has the highest photoactivity.
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Evaluation of pollutant impact on photographic images
Brablc, Tomáš ; Reháková, Milena (referee) ; Veselý, Michal (advisor)
This diploma thesis deals with the impact of pollutants on colour photography made by inkjet printing technology. There are summarized basic principles of inkjet printing, composition of inks and negative factors influencing the printout quality. The ozone was studied in the experimental part, because it has the stongest degrading effect of all common pollutants. The accelerated ageing test with changing the concentration of ozone and the time of exposure was performed. The test scales were made by using two different inks. The L*a*b* values and optical densities of selected fields were calculated from the reflectance spectra of 918 colour fileds. The colour gamut and its volume were calculated from the L*a*b* values. The changes of colour gamut volume correlated with the changes of optical densities. It emerged that using the colour gamut as the instrument of evaluation of the inkjet printout dyes degradation rate is eligible and it is suitable to recommend this method for the ozone accelerated tests.
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Dynamic Decoder for Speech Recognition
Veselý, Michal ; Glembek, Ondřej (referee) ; Schwarz, Petr (advisor)
The result of this work is a fully working and significantly optimized implementation of a dynamic decoder. This decoder is based on dynamic recognition network generation and decoding by a modified version of the Token Passing algorithm. The implemented solution provides very similar results to the original static decoder from BSCORE (API of Phonexia company). Compared to BSCORE this implementation offers significant reduction of memory usage. This makes use of more complex language models possible. It also facilitates integration the speech recognition to some mobile devices or dynamic adding of new words to the system.
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Photochemical degradation of azo-dyes
Uhrová, Ivana ; Čeppan, Michal (referee) ; Veselý, Michal (advisor)
The diploma thesis describes monitoring of photocatalytic activity of titanium dioxide thin films and photocatalytic degradation of azo dyes, the degradation was also experimentally researched in thin film with polymer matrix. Suitable dye for construction of optical sensor for UV light was chosen from the rate of the azo dyes fading by UV and VIS light. The bleaching rate of the sensors was influenced by addition of another dye into the composition and also by concentration of photocatalyst, polymer and calibration agents. At the end of this thesis, the reciprocity test of prepared compositions was made.
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Printing inks optimization for ozone dosimeter
Petříčková, Zuzana ; Krystyník,, Pavel (referee) ; Veselý, Michal (advisor)
In the study various methods to measure concentration of ozone were investigated. Emphasis was placed on opto-chemical sensors, which change their colour when exposed to augmented dose of the substance. Numerous solutions have been prepared by changing ratios of substances and were used to make ozone dosimeter. The goal was to produce highly sensitive composition which would change colour noticeably when exposed to ozone, with good mechanical properties when dried up. When the solution with required properties had been discovered, it is suitably for silk-screen printing was tested.
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